The present invention relates in general to a chip coater and pertains, more particularly, to an improved method for applying a bonding material such as an epoxy glue to the surface of a circuit chip; the method forming one of a number of different steps used in securing circuit chips to a substrate such as a printed circuit or ceramic board.
In the fabrication of hybrid circuits, the steps that are followed generally include the steps of picking up a chip at one location, bringing the circuit chip to another location where it is subjected to a coating, and thereafter, moving the chip to a third location where the chip is properly aligned and oriented with a substrate upon which it is being secured by means of the material, such as epoxy. The movement between these different stations where the method is performed usually occurs by use of a rotating or traversing mechanism having the vacuum chuck for picking up the circuit chip. A problem has been encountered, however, when the circuit chip is lowered into the material so that the undersurface of the chip may be coated with a bonding film. The problem is that many times the surface tension between the circuit chip and the material, such as an epoxy bath, is sufficient to disengage the circuit chip from the vacuum chuck. This is most troublesome in that it interrupts the normal sequence of steps and also requires that the equipment be set up again for operation.
Accordingly, an object of the present invention is to provide an improved method for applying a uniform adhesive film to a circuit chip without the usual attendant problem of disengaging the chip from the vacuum chuck. The uniformity of the epoxy is improved with the adhesive passing through a screen directly onto the chip.